It is common for PBX call attempts to fail because a called party is absent from the location of his/her telephone, or occupied in an important task and so unable to answer the call. It is known in the PBX and CO arts to provide an “Automatic Callback” (ACB) feature whereby a caller presented with a busy or no answer condition can request that a call to the busy called party be initiated the next time the called party is available at his/her telephone (e.g. when the called party next places his/her telephone on hook). With ACB feature activated, the calling party's telephone provides a special indication (e.g. a special ring which may or may not be complemented by a display message) to indicate that the called back party is available. The calling party then goes off hook, or gives some other indication to the PBX or CO, and the call to the called party is automatically attempted.
However, the traditional ACB feature suffers from a number of drawbacks. For example, the indication of availability provided to the PBX or CO is very coarse. A user may be ‘available’ for an urgent call notwithstanding that the user's phone has not gone off hook in a while. Thus, an urgent call may go unanswered for a long period of time while the PBX or CO awaits the coarse indication of availability (i.e. the called party's telephone going off and then on hook). Conversely, the mere fact that a user's phone is on hook does not necessarily mean that the user is available to receive calls. The user may be dealing with others in the room, or conducting other business. Also, the ACB feature was developed at a time when portable wireless devices were not common. Portable devices exacerbate the drawbacks discussed above.
In addition to ACB, numerous other PBX features are known in the art for addressing the problem of an absent or busy user, such as call forwarding, voice mail, cellular twinning, presence and availability, and context-aware and ‘hypothetical’ call processing.
With call forwarding, a user can route calls to telephones that are near him/her when away from his/her primary extension. However, like the traditional ACB feature, call forwarding does not discriminate between urgent and routine incoming calls. Thus, a user might be involved in a business meeting with important visitors and therefore not wish to be disturbed by routine calls.
With voice mail, a calling party is provided with the option of leaving a voice mail message for a busy called party. However, this may not be an adequate solution for urgent calls.
Cellular twinning of a user's primary extension to a portable wireless device overcomes the problem inherent with call forwarding of being required to remember to program valid forwarding numbers. However, it does nothing to solve the other issues of indiscriminate calls being received when the user is involved with other matters. The use of ACB only amplifies the intrusiveness and disruption of ringing a wireless device in inappropriate situations.
Presence services are an emerging technology that provide information of user's availability and capabilities. Such presence services are primarily used for providing availability information of one or more users to another user of a system. This availability information includes an indication of availability or willingness of the user to engage in immediate communication. For example, Microsoft® Live Communication Server (LCS) may be configured to provide availability indicators in desktop computer applications or smart telephony device applications such that a user is provided with availability information of another user, prior to initiating communication, such as making a telephone call. However, commonly available IM systems require the user to manually set his/her availability. Errors are known to occur when a busy user neglects to continually update his/her availability status indicator. Even in implementations in which the user's status may be set automatically (e.g. an away indication being set and removed by absence and presence of computer use), the system has no way of discriminating between urgent and routine incoming calls. Also, in order to use the availability information a caller must constantly monitor the potential called party's availability, which is a time consuming and difficult task.
Context-aware call processing and hypothetical call processing systems are set forth in US Patent Publication No. US 20050100157 entitled Context Aware Call Handling System (Gray et al), the contents of which are incorporated herein by reference. According to Gray et al, a system is provided in which calls are completed according to policies which are sensitive to the ‘fit’ of the call within the called and calling party's context. The system of Gray et al addresses the drawback discussed above of inappropriate calls being placed to unavailable users whose phones may, nonetheless, be off hook.
An availability determination system is set forth in US Patent Publication No. US 20040037396 entitled Generation of Availability Indicators from Call Control Policies for Presence Enabled Telephony Systems (Gray et al), the contents of which are incorporated herein by reference, using the context-aware system of US 20050100157. Availability is determined for individual calling parties in specific contexts by querying the call processing for a proposed action based on a hypothetical incoming call. Call processing returns notifications of availability to potential calling parties any time there is a change in the called party's availability. The availability indicators of US 2004037396 address the issue of inappropriate use of devices by providing an accurate recommendation about user availability in his/her current context. Nonetheless, the systems of Gray et al still require a calling party to constantly monitor a called party's availability.